Vehicle switch for back-up warning



Jan. l, 1952 B. H. HADLEY VEHICLE SWITCH FOR BACK-UP WARNING 2Sl-lE'ETS-Sl-IEET l Filed Oct. 13, 1945 EW 7H: Fuz/w Arrow/Ens Jan.1,1952 l BHHADLEY 2,580,677

VEHICLE SWITCH FOR BACK-UP WARNING Filed Oct. 13, 1945 2 SHEETS-#SHEET 2j. l 'I 2 gffg [we-Nro@ 55m/@MIN H. HHDLEY Patented Jan. 1, 1952 UNITEDSTATES PATENT OFFICE VEHICLE SWITCH FOR BACK-UP WARNING Benjamin H.Hadley, Pomona, Calif. Application October 13, 1945, Serial No. 622,116

(Cl. 20o-52) 7 Claims. 1

My invention relates to electric switches and. more particularly, toautomatic safety signals. either visible or audible, for warning personsof impending danger from rearwardly travelling vehicle.

As recognized by certain State statutes, the. necessity of increasingpersonal safety by equipping automotive vehicles with automatic signalsof this nature has become very important, particularly in the truckingindustry, since the drivers rearward field of view is frequently limitedor obstructed. Many personal injuries and extensive property damage haveresulted from the absence, or improper functioning, of such warningdevices for indicating rearward motion of a vehicle. v I

An object of this invention is to` provide a. simple, fool-proof,reliable warning system of this type.

Another object of this invention is to provide a novel attachmentadapted for quick installation in conventional automotive vehicles.

A further object of my invention is to provide an automatic contactmeans for intermittently energizing an electric circuit; also, toconnect such a contact means for periodically actuating a warning signalat a frequency which is proportional to the rearward velocity of avehicle.

Still another object of my invention is to pro vide a warning circuitwhich is not energized unless both of two automatic switches are closedin series relationship. As applied to a vehicle warning system, theinvention includes a primary control switch electrically responsive onlyto reversed rotation of a speedometer cable, and e. secondaryoscillatory switch intermittently responsive to any rotation of thespeedometer cable, these switches cooperating to actuate a warningsignal only during the actual rearward motion of the vehicle.

A further object of my invention lies in the provision of a novelautomatic friction clutch for motivating a control switch.

Certain other objects of my invention are achieved by providing aself-contained adapter or coupling unit having the aforesaid controlswitch and/or the oscillatory switch installed therein, this couplingunit being readily connectable to the speedometer drive of a vehicle.Alternatively, however, this novel adapter or coupling unit may beregarded as a driven unit which may be readily adapted for connectionwith, or actuation by, any other driving member which rotates forwardlyor rearwardly in response to forward or rearward motion of theautomotive vehicle or in response to other means.

Additional objects and advantages of the invention will be evident tothose skilled in the art from the following description of an exemplaryembodiment.

Referring to the drawings:

Fig. 1 is a. schematic diagram of an electrical circuit for utilizingthe invention;

Fig. 2 is a longitudinal sectional view of the adapter showing theautomatic electrical switches installed therein; l

Fig. 3 is a transverse sectional view, taken along the line 3-3 of Fig.2, showing the oscillatory or intermittent switch of the invention;

Fig. 4 is a transverse sectional view, taken along the line 4--4 of Fig.2, showing the control switch of the invention;

Fig. 5 is a. longitudinal sectional view of an alternative embodiment ofthe adapter;

Fig. 6 is a transverse sectional view, taken along the line 6--6 of Fig.5;

Figs. 7 to 10 illustrate a modified embodiment, Figs. 7 and 8 beingtaken similarly to Figs. 2 and 4,' while Figs. 9 and 10 are enlargedviews of the modied contact assembly of the modied control switch,respectively in closed and open posi.- tions;

Figs. 1l and 12 show a modification in which the modified control switchis incorporated alone in the adapter, being taken similarly to Figs. 5and 6; and

Fig. 13 is a wiring diagram showing a connection for the embodiments ofFigs. 5, 6, l1, and 12.

A general introduction to the invention may be obtained by referring toFig. l. In order to increase personal safety and prevent inadvertentdestruction of property, an automotive vehicle should be equipped withan automatic electrical warning circuit lil, which intermittentlyactuates a signaling device I l as long as the vehicle travelsrearwardly. The frequency of the intermittent signal is desirablydetermined `by the rate of rearward movement to indicate the degree ofimpending danger. As shown diagrammatically in Fig. l, the inventionaccomplishes these purposes by use of a control switch l2 closed onlyduring actual rearward movement of the vehicle and connected seriallythe warning circuit l0 with an intermittent switch I3, which opens andcloses upon motion of the vehicle in either a forward or reversedirection. The warning circuit I0 may be com.- pleted through a manualswitch M, desirably the Yby the circuit I3.

`ber 23 of the housing 2B. 4and 3 where the details of ignition switchof the vehicle, and this circuit such as a battery I5 of the vehicle.

Various signaling devices lI may be employed for emitting visible oraudible warnings, for example, an electromagnetically actuated gonghaving a metallic resonator or bell I6 struck by a hammer VIl to emit asingle warning signal each time a solenoid IB is electrically energizedbe installed in the vehicle in any appropriate manner or position. Ifvisible signals I9, such as flashing colored lights, are desired, theymay be electrically connected in parallel with the signaling device II,or substituted therefor.

As best shown in Figs. 1, 2, 3, and 4, the control switch I2 and theintermittent switch `I3 Such signalingv devices may are housed in anadapter unit 23 interposed in the speedometer drive of the Vehicle orconnected to some element of the vehicle which turns in oppositedirections upon actual forward and reverse movement of the vehicle. Asillustrated, the vehicle includes a transmission 2| having a threadedspeedometer drive connection 22 to which is normally connected acoupling 23 of a speedometer conduit 24 carrying the usual square-endedflexible speedometer drive member, the square end normally extendinginto a squared opening of a rotary member 25 driven f by thetransmission 2l. v The adapter unit 20 includes a housing 26 comprisinga cylindrical body member 21 and a head member 28 cooperating indefining a chamber 23.- The members 21 and 28 are held together bycountersunk screws 30, passing through a ange 3l of the body member 21and threaded into an annular wall 32 of the head member 28. The bodymember 21 has an axial bore 33 providing a counterbore for engagementwith the speedometer drive connection 22. Within the axial bore 33 arepressed two sleeves 34 which serve as bearings for a rotary shaft 35whose ends have axially-disposed apertures 35, 31, preferably of squarecross section, which allow the shaft 35 to be interposed in thespeedometer drive of the vehicle. In this connection, the squaredaperture 33 may receive one square end of a stub shaft 38, the othersquare end of this stub shaft tting into the aforesaid squared openingof the rotary member 25. The two sleeves 34 are spaced from each otherto provide an annular space containing an annular sealing ring 39,preferably of doughnut shape and formed of rubber.

Similarly, the head member 28 provides a bore 4B axially aligned withthe bore 33 and in which are pressed sleeves 4I spaced to form anannular space providing a sealing ring 42 similar to the ring 39. Thesesealing rings resiliently engage the peripheryv of thevshaft 35 to formeffective grease seals forl sealing within the chamber 23 any lubricanttherein and for preventing entry into this chamber of any libricant.from the transmission 2l or from the speedometer conduit 24. The headmember 28 isexternally threaded to receive the coupling 23. The squareend of the flexible speedometer drive member positioned within thespeedometer conduit 24 extends into the aperture 31 of the n Ishaft 35.

The intermittent switch I3 is within the cham.- Referring to Figs. 2this intermittent switch are best shown, the shaft 35 carries a cam 43separated from the flange 3| by a washer l 4 44. The cam surface of thecam 43 1s shown as hexagonal and is engaged by a follower 45 of acontact arm 45 pivoted on a pin 41 carried by the flange 3l. Thefollower' 45 is resiliently urged into contact with the cam 43 by aresilient member 48, exemplified as a band of spring steel with one endlooping around the journalled end of the contact arm 46 and providing ahook 49 engaging same, Cthe other end being flexed inwardly duringassembly of the body member 21 and the head member 23 to bear againstthe inner surface cf the annular wall 32 of the head member. Y

The intermittent switch I3 includes a pair of make-and-break contacts,shown as including a movable contact carried by the end of the contactarm 45 and an adjustable stationary contact 5I provided by the end of anadjusting screw 52. As best shown in Figs. 2 and 3, this adjusting.screw extends through a threaded bore 53" of a post 54 formed ofinsulating material, this post providing ears 55 secured to the flange3l, as by screws 55. The threaded bore 53 extends parallel to the flange3I and a saw-cutJ 53 extends from the outer surface of the post to thisthreaded'bore. This saw-cut is traversed by a screw 53 to contract thematerial of the post 54 against the adjusting screw 52 in clampingrelationship. By loosening the screw 59, the adjusting screw 52 can beadjusted for any desired maximum clearance between the contacts 5o and5I', this adjustmentvarying the interval ottime which elapses whilethese contacts are engaged.

` The preferred setting is such that the periods to energize thesignaling of engagement of these contacts are of shorter duration thanthe periods of disengagement and so that the follower 45 engages onlythe crests of the cam 43.

` The control switch I2 is connected is series with the intermittentswitch I3 andl includes, in general, a stationary control contact 60, amovable control contact 6I, and an auxiliarycontrol contact 32. Thefunction of the control switch I2 is to render the intermittent switchI3 operative device II only during rearward movement of the vehicle. Forthis purpose, the control switch is actuated by a friction drive, to belater described in detail.

The construction of the control switch I2 is best shown in Figs. 2, 3,and Referring thereto, the stationary control contact 63 is formed bythe end of a pin 6 3 pressed into a bore extending perpendicular to theflange 3l, as best shown in Fig. 2. This bore intersects the threadedbore 53 to permit the pin 63 vto be electrically connected to theadjusting screwr 52 to place the control switch I2 and the intermittentswitch I3 in series relationship. Preferably, the pin 53 is positionedin its bore before the bore 53 is drilled and threaded, wherefore aportion of the threads of the bore 53 is cut in the pin 33, thusinsuring good electrical contact between the adjusting screw 52 and thepin 63.

The auxiliary control contact 62 is a part of a strap 35 formed ofspring material and held in place by the screw 59. It provides aresilient offset p ortion terminating in a resilient brush contact ortab 5t permanently spaced from the stationary control contact 6G butadapted to be engaged by the movable control contact 5I in vits movementtoward the stationary control contact 33, as will be later described indetail. The-movable control contact 5I bridges between the auxiliarycontrol contact 52 and the stationary control contact 60 to completethe, 'to 'the signaling device I I.

It will be readily .apparent the auxiliary, Qontrol contact-'62 ,Shouldbe insulated .irorn'tha housing 2 5, yet connectable to the Warning cirecuit I0.

tionally engaging the head of a bolt B8 extend-ing through the annularwall 42 and :insulated thereA 68 which, as suggested -in Fig. 1. isconnected in.

the warningr circuit In. fljhus, when the yhead member '28 is moved fromthe body member 21,. the head of the bojlt 68 slides along the resilient.contact .61.. In reassembling the members 2l, 2B.. it is .onlynecessary to 4orient the member -28 angularly with respect to the member2l .so that the head of the boit 6B engages the resilient contact-.51..The countersunk screws .3,0 vmaintain this angular orientation.

The friction drive :means :forthe control switch I2 is best shown inFigs. Z and 4. Referring thereto. the shaft k35 provides a. shallowperipheral groove adapted toreceive a. doughnut-.shaped ring ll,preferably formed of resilient material. A peripherally-continuousrubber ring is pre-V ferred, this ring having :such an internal diameteras to move along the periphery of :the shaft 3'5 and drop into thevshallow groove 1I) to be .in frictional engagement with the bottom ofthis groove. The ring .'II is .carried in an annular groove v'I2 of acollar I4 .of an .internal diameter to vbe freely rotatable relative tothe shaft .35. A washer 15 separates the collar M from the head member28. The .collar 14 is peripherally sur,- rounded by a ring of insulatingmaterial l5 .and

a ring 1l, the latter carrying the movable con-I trol contact 6I. Theinsulating ring 'I6 is vcorripressed between the ring 'Il and the collarMito insulate the movable control contact 6I from the collar, whileinsuring Ythat this movable control contact 6I shall move rigidly withthe collar. i

As best shown in Fig. 4, the movable control contact 6I is in the formof a blade 'I8 rotatable about the axis of the Shaft 35 between limitingpositions. When the vehicle is moving in a forward direction, the shaft3-5 moves clockwiseLes viewed in Fig. 4, and :the friction. drive meansmoves the blade'l intoA contact with a Vstop means, shown as comprisinga pin 80 .carried `the flange 31. This 'pin' 80 'is either 03116@ 0finsulating materiale? vis suitably insulated from the body member 21.When the vehicle nieves rearwardly, the shaft 315 turnscounter-clockwise, as viewed in Fig. 4. and the 'blade I8 and its moveable control contact .6l rst engage, and are energized by, the resilienttab 6.5 of the euxiliary control .Contact 62, .after which a furtheryand very small counter-.clockwise movement brings this movable controlcontact :into circuit-closing engagement with the stationary control.contact i0. Thus, during this last portion of its move.- ment, themovable control contact il bridges between -the auxiliary controlcontact 62 and the Vstationary control Contact S8 to connect the' intermittent Switch I3 .serially tbe'warnine cir# Cuit I0. The totalangular movement of the `niovable control contact v,6.I between itslimiting posi.- tions, is .small so that the control switch I2 closesbefore the vehicle is moved backward anyfsiibstantial distance.`Continued rearward movement of the vehicle will cause energization ofthe This is accomplished by bending the strap AI5 to provide aresilientwcontact 6l fricwarning circuit il under the action of theinter :ottieni: 4switch I 3. at a frequency proportional to the rearwardvelocity or. the vehicle To reduce eroine between the contacts, of, 'theintermittent switch and the conta-cts 6|., 62 or control switch. andalso lto store electrical-onere! for the bell 16 thus aiding in therpercussive blows. of the hammer il., I prefer to :connect n con: denser8i aground the two pairs of contacts. .As suggested in Figs. 1 and3.1one terminal of condenser :is grounded to the frame of the we 'hiclethrough a .clip 82 and a screw f83 :securing the condenser to the flange3i of the body mem-` ber 21, The other terminal of fthe condenser-:Il isconnected by a lead `IM to ythe strap '65. this lead carrying theterminal .extending beneath the head-ofthescrew 59.

The friction .drive means Afor 'the control switch I2 comprises Yany.means for moving the movable control contact 6rI between .its limitingpositions noon forward and vvreverse movement of the 'vos` hic'le,respectively. The embodiment .of the frio, tion drive means shown inFig. 2is particularly valuable in this connection. The arrangementpermits the collar III :and its .associated ring zlfI to befslippedlongitudinally over the end of the shaft 35 when the head member 28 isremoved. When the ring 1l .drops into the shallow groove 'III itresiliently holds 'the collar I4 in the correct ax ia'l position. In thepreferred arrangement, the ring rII nts Arather snugly in the annularygroove so' that the `sliding ltakes place between the' ring H and thebottom of the groove I0 of the shaft. However, if desired, .the annulargroove I2 may .be made .slightly larger .so that the sliding 'takesplace lbetween the ring 1 I .and the walls of this annular groove 12,the ring then'rotating with the .shazft 35. Alternatively, sliding canbe .made to ltalee place at both positions. There is lvery littlefwearon the ring 1I, Aparticularly'if it is formed .of ysynthetic rubber andits periphery is properly lubricated, as by lling the unoccupied`por-tion of the groove 112 with a light oil.

'Bhe control .switch I2 Yof the invention canA be employed independentlyof the intermittent .switch I3, las suggested in Figs. 5 and `6. Here; ahousing 7|26 4is formed by a body member '|21 and ahead ,member I28,these members cooperating in providing a chamber y|29 through whichasshaft 4.55 extends.

fore, this .form of the invention includes asta.- tionary :controlcontact |50, a movable control contact ISI vand an 4auxiliary controlloi1l1l-lii FI $3, The stationary control Contact .|60 is formed by theend of a pin iss which, in this instance ci tends through the post |54to be grounded to the frame of the vehicle through the 'body mein'.-'ber 121.

` The auxiliary control contact ['62 is constructed as previouslymentioned and includes a resilient tab |66 engageabie by the movablecontrol contact IBI before it engages the stationary control contact|69. The friction drive for thel'movable control contact III is aspreviously described, .and

includes a .collar IM frictiona-ly counled with the shaft I 35'andcarrying a ring of insulating mate- .rial ITI-6 surrounded .by a ring H1which confier the 'movable control contact .ISL A pin. 180-11mits thedegree of clockwise movement el" the moy-.- able .control contact IGI,as viewed iniFig. f This embodiment of theinvention iswelladapted to thewarning circuit shown in Fig. 5 wherein a Vconductor 200 is connected tothe auxiliary con.- trol contact 152 and extends to a bell ZM ando A:post Iii-4 formed vof insulating material is mounted in the chamberIZS. .As

signal light-202connected in parallel, the warning circuit beingenergized by a battery 204 and including a control switch 2 I'4 whichmay be the ignition switch of the vehicle. In this instance, the bell isdesirably of the type which gives out intermittent signals so long as itis energized, e. g., it may be of the doorbell type having conventionalmake-and-break contacts associated therewith to give a continuouswarning signal during each period of energization. When the vehiclemoves in a forward direction, the movable control contact |6| is thrownagainst the pin 180 and no warning is given. However, even a smallrearward movement of the vehicle will bridge the movable control contactI6| between the auxiliary control contact |62 and the stationary con-Jtrol contact |60 to complete the warning circuit, this circuit remainingenergized so long as Vthe rearward'movement of the vehicle continues.

".The embodiment of Figs. 7 to 10 is essentially similar to that ofFigs. 2 to 4, with the exception of the use of a-modied control switchconstruction which requires only a few inches of rearward vehiclemovement for actuation. The housing arrangement, the intermittent switch13, and the friction drive therefor are as previously described.However, the stationary control contact 60, the movable control contact6|, and the auxiliary controlcontact 62 of the control switch I2 aredifferently arranged, as follows'. Here, the stationary controlcontactcomprises a pin 263, as before, and the auxiliary control contact formsa tab 266 ofA modified shape. Also, the movable control contactcomprises a narrow arm or blade 218 driven by the friction drive means,and provides a projection 219 which remainsy in sliding engagement withthe tab 266. The pin 80 is replacedl by a stop` member 280 formed on amodified post, indicated at 28 I, andformed of insulating-v material, asbefore. -The distance betweeny the -pin 263 and the stop member 280 isonly slightly larger than the arm or blade 218 so that only a smallamount of rearward vehicle movement is required-to move it from its Fig.10

position, assumed during forward motion of the vehicle and retainedduring the time the vehicle is stopped, to its Fig. 9 position, assumedduring rearward.A motion of the vehicle. In the' vlatter position," thearm or blade 218 electrically connects the auxiliary control contact 62with the 'y pin 263 of -the stationary control contact 60 to connecttheintermittent switch in circuit.

A Figs. 11 and 12 show the same modified control 'swtch'alo'nein thehousing and the main elegr'nents are identical with the embodiment ofFigs.

v1.71.@0'101 'except that the intermittent switch 1:', is omitted andasin Fig. 5, the pin 263 is directly grounded to the housing. Thisembodiment can lbeconnected in circuit witha make-and-break .type bellor a back-up light illuminating th rearward pathof the vehicle, or both..s

Another circuit, designed to give a viiashing signal whether visual or'audible is suggested in Fig. 13, in which the embodiment of theinvention shown in Figs. 11 and 12 is indicated at 250 asconnectedserially with a manual control or ignition switch a thermalvswitch 252,and Va'warning device 253.' The thjer'mal'switch'isl of themake-andbreak type with Ar'iormall'y-closed contactsV 255 and 256disengaged by bending'of a bimetallic strip 251 vheated by a heaterwinding '258 serially connected in the circuit through contacts,25 5.and 256. In this instance, ,the

f'frequency ofthe signal will be determined by the rate of heating andvcooling of the bimetallic strip 258.

Various changes and modications can be made without departing from thespirit of the inven tion as dened in the appended claims.

I I claim as my invention:

1. In a back-up warning switch adapted for connection to a speedometerdrive connection of a vehicle, said drive connection providing` a rotaryLmember rotatable in forward and reverse directionsupon forward andreverse movement of said vehicle, and adapted to energize a circuitduring movement only "in such reverse direction, said switch includingin combination: a housing attachable to said speedometer driveconnection and providing a chamber'extending around an axis; a shaftjournalled in said housing to turn about said axis and extending intosaid chamber, said` 'shaft being adapted for connection to said rotarymember to turn therewith in forward and reverse directions; a stationarycontrol contact in said chamber; a movable control contact in saidchamber extending outwardly from said shaft;l an electrically insulatedstop means in said chamber, said movable control contact being disposedto move between said stationary control contact and said stop means, thedistance between said stationary control contact and said stop meansbeing only slightly greater than the width of said movable controlcontact; and friction drive means for connecting said shaft to saidmovable control contact to move same into engagement with saidstationary control contact during reverse movement of said shaft and tomove same into engagement withV said stop means upon forward movement ofsaid shaft, said friction drive means including a collar surroundingsaid shaft and a resilient member ofl rubber-like material clampedbetween and resiliently'engaging said collar and said shaft.

2,'In a back-up'warning switch adapted for connection to a speedometerdrive connection of a vehicle, said drive connection providing `a rotarymember rotatable in forwardand reverse directions upon forward andreverse movement of said vehicle, and adapted to energize a circuitduring movement only in such reverse direction, said-switch including incombination: a housing attachable to said speedometer drive connectionand providing a chamber extending around an axis; a shaft journalled insaid housing to turn about said axis and extending into said'ch'amber;said shaft being adapted for connection to said rotary member to turntherewith in forward and reverse directions; a stationary [controlcontact in said chamber; a movable controlcontact in said chamberextending outwardlyfrom said shaft; an electrically insulated 'stopmeans in said chamber, said mov able control contact being disposed tomove between said stationary control contact and said "stop means, thedistance between said stationary control contact and/said stop meansbeing only 'slightly greater than the width of said movable controlcontact; and friction drive means for connecting said shaft` to saidmovable control contact to move same into engagement with saidstationary vcontrol contact duringreverse movement'of said shaft and tomove same' into eng'agernent with said stop `means upon forward movementof said shaft, said' shaft providing a shallow peripheral' groove, saidfriction ldrive means including a collar surrounding said shaft andincluding aring of resilient, rubber-like materialdn said shallow grooveand clamped :a bctweensaid collar and said shaft to form a frictiondrive-for said collar.

3. .In a back-up warning switch adapted for connection to a speedometerdrive connection of :a vehicle, said drive connection vproviding arotary member rotatable in forward and reverse .directions upon forwardand reverse movement of said vehicle, and adapted to energize a circuitduring movement only in such reverse di.-

vrection, said switch including in combination:

a housing attachable to said speedometer drive connection and providinga chamber; a shaft journalledin said housing. and extending into saidchamber, said shaft being adapted for connection to saidrotary member toturn therewith in forward and reverse directions; astationary controlcontact in said chamber, said stationary control contact being adaptedto be electrically connected to said housing; an auxiliary controlcontact in said chamber, said auxiliary control contact and saidstationary control contact being connectible in said circuit, saidauxiliary control contact being insulated from said housing; a stopmeans in said chamber; 'a movable control contact in said cham-ber; anda friction drive means operatively associated Vwith said shaft and saidmovable control contact .to move said movable .control contact againstsaid stop means upon forward rotation of -said shaft and .to ,move samein bridging relationship between said auxiliary control contact and saidstationary control contact upon reverse rotation of said shaft, saidfriction drive means including a collar surrounding said shaft, a ringof resilient material frictionally` engaging said collar and said shaft,and insulating means for mounting said movable control contact to movewith said collar while electrically insulated therefrom.

4. In a back-up warning switch adapted for connection to a speedometerdrive connection of a vehicle, said drive connection providing a rotarymember rotatable in forward and reverse directions upon forward andreverse movement of said vehicle, and adapted to energize a circuitintermittently during movement only in such reverse direction, saidswitch including in combination: a housing attachable to saidspeedometer drive connection and providing a chamber; a shaft journalledin said housing and extending into said chamber, said shaft beingadapted for connection to Asaid rotaryl member to turn therewith inforward and reverse directions; an intermittent switch in said chamberand comprising a stationary contact, a movable contact, a contact armcarrying said movable contact, and a cam carried by said shaft formoving said contact arm to engage said movable and stationary' contactsintermittently during rotation of said shaft in said forward and reversedirections; a control switch in said chamber, said control switchincluding a stationary control contact, a movable control contact, and astop means, said movable control contact being disposed to move betweensaid stationary control contact and said stop means; friction drivemeans for connecting said shaft to said movable control contact to movesame into engagement with said stationary control contact during reversemovement of said shaft and to move same into engagement with said stopmeans upon forward movement of said shaft, said friction drive meansincluding a collar in said chamber surrounding said shaft adjacent saidcam, and a resilient member between and resill0 iently engaging saidcollar and said shaft; and means for serially connecting said contactsof said intermittent switch and said control contacts of said controlswitch.

5. In a back-up warning switch adapted for connection to a speedometerdrive connection of a vehicle, said drive connection providing a rotarymember rotatable in forward and reverse directions upon forward andreverse movement of said vehicle, and adapted to energize a circuitintermittently during movement only in such reverse direction, saidswitch including in combination: a housing attachable to said speed'-ometer drive connection and providing a cham- ,ber'ya .shaft journalledinsaid housing and extending into said chamber, said shaft being.adapted for connection to said rotary member to turn therewith inforward and reverse directions; an intermittent switch in said chamberand comprising a stationary contact, a movable contact, a contact armcarrying said movable contact, and a cam carried by said shaft formoving said contact arm to engage said movable and stationary contactsintermittently during rotation of said shaft in saidV forward andreverse directions; a control switch in Said chamber, said controlswitch including a stationary control contact, a movable controlcontact, andastop means, said-movable control contact being disposed tomove between said stationary control contact and said stop means;friction drive means for connecting said shaft -to said movable controlcontact to move same into engagement with said stationary controlcontact during reverse movement of said shaft and to 'move same intoengagement with said stop means upon forward movement of said shaft,said. shaft providing a shallow peripheral groove and said frictiondrive means including a collar surrounding said shaft and a ring ofresilient material in said shallow groove and engaging said collar toform a friction drive for said co1- la'r; and means for seriallyconnecting said contacts of said intermittent switch and said controlcontact of said control switch.

6. In a back-up warning switch adapted for connection to a speedometerdrive connection of a vehicle, said drive .connection providing a rotarymember rotatable in forward and reverse directions upon forward andreverse movement of said vehicle, and adapted to energize a circuitintermittently during movement only in such. reverse direction, saidswitch including in combination: Aa housing attachable to saidspeedometer drive connection and providing a chamber; a shaft journalledin said housing and extending intov said chamber, said shaft beingadapted for connection to said rotary member to turn therewith inforward and reverse directions; an intermittent switch in. said chamberand comprising a stationary contact, a movable contact, a contact armcarrying saidmovable contact, and a cam carried by said shaft.

for moving said contact arm t0 engage said movable and stationarycontacts intermittently during rotation of said shaft in said forwardand reverse directions; a control switch in said chamber, said controlswitch including a stationary control contact, a movable controlcontact, and a stop means, said movable control contact being disposedto move between said stationary control contact and said stop means,said control switch including an auxiliary con- 75 trol contactengageable with said movable control contact before the latter engagessaid staftionary control contact whereby said movable control contactbridges between and electrically connects said auxiliary control contactand said stationary control contact; friction drive means for connectingsaid shaft to said movable control contact to move same into engagementwith said stationary control contact during reverse movement of saidshaft and to move same into engagement with said stop means upon forwardmovement of said shaft; and means for serially connecting said contactsof said intermittent switch and said control contacts of said controlswitch.

- 7. A one-way switch adapted for connection to a rotary memberrotatable in both forward and reverse directions and adapted to energizea circuit during movement of said rotary member only in such reversedirection, said switch including in combination: a shaft including meansfor connecting same to said rotary member to turn therewith in forwardand reverse directions; a housing providing a chamber disposed aroundsaid shaft, said housing providing bearing means for journalling saidshaft; a movable control contact blade; a friction drive means forconnecting said movable blade to said shaft to move said blade in saidchamber in an arcuate path in forward and reverse directions uponforward and reverse movements of said shaft; a stationary controlcontact projecting into the path of arcuate movement of said movableblade to act as a stop for said blade during reverse motion thereof andto contact same electrically, thus limiting the reverse motion of saidblade while permitting continued reverse motion of said shaft throughslippage of said friction drive means; a stop member projecting into thepath of arcuate movement of said movable blade to limit the forwardmotion thereof while permita ting continued forward motion of said shaftthrough slippage of said friction drive means. said stop member beingdisplaced.` from said stationary control contact an arcuate distanceonly slightly greater than the arcuate width of said blade and acting tostop any forward motion of said blade shortly after electricaldisengagement of said blade and said stationary control contact; meansfor electrically insulating said movable blade from said shaft and fromsaid housing; and a brush contact extending into said arcuate path ofsaid blade to engage and energize said blade before it contacts saidstationary control contact upon reverse movement of said blade.

BENJAMIN H. HADLEY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 564,168 Tower July 14, 1896874,289 Bemus Deel 17, 1907 915,891 Schaake et al Mar. 23, 19091,273,378 Kennington July 28, 1918 1,394,032 McKeown Oct. 18, 19211,482,167 Varley Jan. 29, 1924 i 1,703,319 Patterson et al Feb. 29, 19292,132,188 Rockett et al. Oct. 4, 1938 2,139,482 Atz, Jr. Dec. 6, 19382,143,447 Moeller Jan. 10, 1939 FOREIGN PATENTS Number Country DateGermany Apr. 30, 1931

